Hello, Thank you for the suggestion, seems the way to go. I have implemented this using both variable descriptor and prepared statement (execquery) in my program and it works nicely, except in one specific situation. What I didn't mention previously is that we are sometimes using 2 connections in the same thread: 1 for reading some tables (doing SELECT), and 1 for writing other tables (doing INSERTs/UPDATEs) for each record from the first, after some complex operations on the data. In this case when I deallocate the execquery (and descriptor) I get an error from the ecpg lib saying: -230:26000 invalid statement name Debugging into the ecpglib, I see that when 'get_connection()' is called (from ECPGdeallocate()) with NULL as parameter, it returns the wrong connection and then uses this and the query name in a call to 'find_prepared_statement()' which of course doesn't find any because of the mismatch of name and connection, hence the error message. Is it really not possible to use 2 separate connection within 1 thread at the same time ? or is it an error in the ecpg library ? Please help, Leif ----- "Bosco Rama" <postgres@xxxxxxxxxxxxx> wrote: > Leif Jensen wrote: > > > > This seems to be working most of the time, but looking at the > generated C > > code from the ecpg compiler and the associated library functions, we > are > > not sure whether we should put mutex locks around the 'select' part > to > > avoid several threads are using "the same" execdesc at the same > time. > > > > We have made sure that each thread uses their own and only their > own > > database connection, but are unsure whether the ecpg library > functions is > > able to handle multiple use of the statical name "execdesc" ? > > You are most probably trashing memory by using the same descriptor > name in > multiple threads. However, given that you have already spent the > effort to > have the connections 'thread-dedicated' I think that rather than > creating a > critical path through an area that is intentionally supposed to be > mutli- > hreaded, I'd be inclined to use the connection name (or some > derivation of > it) as the name of the descriptor. I haven't used descriptors in ecpg > so I > don't know if the syntax works, but you could try: > > exec sql char *dname = _thisDbConn; // Or some derivation > > EXEC SQL AT :_thisDbConn ALLOCATE DESCRIPTOR :dname; > ... > EXEC SQL AT :_thisDbConn FETCH IN execcurs INTO SQL DESCRIPTOR > :dname; > ... > EXEC SQL DEALLOCATE DESCRIPTOR :dname; > > > Just a thought. > > Bosco. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
